Tape drive apparatus with a head alignment system

ABSTRACT

A tape drive apparatus is provided with a base plate and tape path components on this base plate. The apparatus includes a bracket that is adjustably coupled to the base plate, the path components carrying a magnetic head for reading and writing to a tape transported by the path components. Pre-loaded jackscrews of the adjustment couplings are rotated to adjust and lock the azimuth and zenith settings for the magnetic head. A separate penetration screw independently controls the penetration of the magnetic tape.

RELATED APPLICATIONS

This application claims priority to provisional application serialnumber 60/337,288, filed on Nov. 30 2001, and utility application serialnumber 10/259,524, filed Sep. 30, 2002. Further, the disclosures of boththese applications are incorporated herein by reference for allpurposes.

FIELD OF THE INVENTIONS

The present invention related to the filed of tape drives, and moreparticularly, to systems for aligning the magnetic head of the tapedrive apparatus.

To perform an optimum magnetic recording on the tape drive apparatus, anaccurate geometric relationship must be maintained between the path ofthe magnetic recording tape and the write-read gaps of the magneticrecording head. This geometric relationship is referred to as the “headalignment.” The head alignment includes the head-to-tape relationship inthree main orientations. The “azimuth” relates to the perpendicularityof the head-gap with respect to the path of the tape. The “zenith”relates to the tilt of the head with respect to the tape. The“penetration” refer's to the amount of penetration of the magnetic headinto the path of the tape. This head penetration controls the wrap angleof the tape with respect to the contour of the magnetic recording head.

Due to the normal manufacturing tolerances of the components of the tapepath and the head positioner of the tape drive head positioningapparatus, the location of the head-gap varies with respect to the tapepath. In light of this, after assembly of the tape drive, it is veryunlikely that the head will be precisely aligned to the tape path withinthe necessary alignment tolerances. Additionally, tape cartridges areoften interchanged between drives. This requires that the data recordedon one cartridge on a tape drive must be able to be read by the samefamily of other tape drives. Hence, each of the tape drives needs tohave its head properly aligned to provide consistency between the tapedrives.

Normally, after the assembly of the head, positioner and the tape pathcomponents, it is common practice to set the head-alignment within therequired limits. This alignment is set at the factory and is consideredone of the most critical procedures in the assembly of the tape drive.However, although this should be considered a final step of theprocedure, conventional practices have often required additional stepsto lock the alignment into place. A concern with this is that thelocking operation itself often causes the alignment to change andrequire repetition of the alignment setting operation.

Another problem present in conventional systems is the potentialmigration of the head or the head positioning system when the tape driveis subjected to a reasonable shock or vibration. When this occurs, thehead alignment changes and affects the write-read performance of thetape drive. Conventional systems strictly rely on fasteners to keep thealignment in place and do not provide adequate protection to secure thealignments against a shock-vibration environment.

The increasing capacity of tape drives requires increasing accuracy ofthe alignment system. In order to achieve this increasing accuracy, thealignment offset must be measured precisely and then corrected using apredictable mechanism. The correction of the measured error to within arequired accuracy requires a fine-resolution in the alignment system.Conventional systems use cams, for example, to set such alignments, butdo not provide for the calibration of the cam rotation to correctcertain skew amounts nor provide a mechanism for rotating these cams.

Another concern with the head alignment systems is the difficulty inre-setting alignments in conventional tape drives without incurringeither a large amount of disassembly or without damaging the tape drive.For instance, certain conventional tape drives employ applying apermanent adhesive to bond ahead placing mechanism in place. If for anyreason the alignment is not within the required specifications, the bondjoint must be broken and in turn, the head may get damaged. In addition,application of the bonding agent near the head element is not apreferred procedure, as the adhesive may get deposited on the headsurface and result in deterioration of write-read processes.

Another concert related to the head-aligning process is the potentialaffecting of the performance of some of the critical components of thetape drive. Certain conventional alignment processes will affect theperformance of certain critical components of the tape drive. This canresult in the reduction in the life of these components or hinder theperformance of the system.

SUMMARY OF THE INVENTION

There is a need for a head-alignment system and process to align amagnetic recording head within a tape drive apparatus within therequired limits, and have this setting be considered a final step of theprocedure. Furthermore, a process and apparatus are needed to provideresistance against any reasonable shock and vibration. At the same time,it is desirable to provide for an accessible alignment mechanism thatallows convenient access to reset the alignment without substantialdisassembly or damage to the tape drive. Furthermore, a predictable andprecise process and apparatus are needed to align the system with thefine resolution needs of modern high-capacity tape drives. There is alsoa need for a system that does not interface with any functionalcomponents of the tape drive or affect the performance of any tape drivecomponents due to the setting requirements.

These and other needs are met by embodiments of the present inventionwhich provide a tape drive apparatus with a head-alignment system,comprising a magnetic head and means for adjusting a spatial orientationof the head with respect to a magnetic tape. In certain embodiments ofthe invention, the means for adjusting is configured to adjust azimuth,zenith and penetration of the magnetic head with respect to a magnetictape. In still further embodiments, the apparatus comprises a baseplate, a tape transport apparatus on the base plate, a bracket thatcarries the magnetic head, and connectors that connect the brackets tothe base plate by an adjustable distance.

The earlier stated needs are also met by other embodiments of theinvention which provide a tape drive apparatus comprising a base plate,tape path components the base plate, and a bracket adjustably coupled tothe base plate. The bracket carries a magnetic head for reading andwriting to a tape transported to tape path components. Adjustmentcouplings couple the brackets to the base plate and are lockablysettable to adjust and lock the spatial orientation of the magnetic headwith respect to a tape transported by the tape path components. Incertain embodiments of the invention, the adjustment couplings includeupwardly extending posts on the bracket, with each post having ascrewhole for receiving a screw. The adjustment couplings also include aspring concentrically surrounding each post and bearing at opposite endsof the spring against the bracket and the base to bias the bracket andthe base away from each other. Screws extend through the base into eachscrew hole, with turning of the screws adjusting the spatialorientation.

The foregoing and other features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view, line diagram schematically depicting the tape pathcomponents of a tape drive apparatus constructed in accordance with theembodiments of the present invention.

FIG. 2 is a perspective view of the internal components of a tape driveapparatus constructed in accordance with an embodiment of the presentinvention.

FIG. 3 is a detail of the internal components of the tape drive of FIG.2, detailing the head alignment system.

FIGS. 4A-4C schematically depict the alignment adjustments of themagnetic recording head in relation to the magnetic recording tapeprovided by the head alignment system in accordance with embodiments ofthe present invention.

FIG. 5 is an exploded view of the internal components of the tape driveapparatus of the present invention, more clearly depicting theadjustment couplings of the head alignment system in accordance withembodiments of the present invention.

FIG. 6 is a detailed perspective view illustrating a penetrationalignment screw of the head alignment system in accordance withembodiments of the present invention.

FIG. 7 shows a head positioner constructed in accordance withembodiments of the present invention.

FIG. 8 depicts a fine positioner assembly with a flexure retainerattached thereto, in accordance with embodiments of the presentinvention.

FIG. 9 shows the flexure retainer in isolation, in accordance withembodiments of the present invention.

FIG. 10 is an exploded view of the head positioner assembly constructedin accordance with embodiments of the present invention.

FIG. 11 shows the assembled head positioner assembly, in accordance withembodiments of the present invention.

FIG. 12 is a cross-section of a pivot point coupling constructed inaccordance with embodiments of the present invention.

FIG. 13 is a cross-section of zenith adjustment coupling or an azimuthadjustment coupling constructed in accordance with embodiments of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention addresses and solves problems related to the headalignment apparatus and processes of conventional tape drive apparatus.These include aligning the head precisely in a controlled manner andmaintaining the head alignment position in a procedure that does notrequire locking of any additional components. This is achieved, in part,by the present invention which provides a base plate that has tape pathcomponents on the base plate and a bracket that is adjustably coupled tothe base plate. This bracket carries a magnetic head for reading andwriting to a tape transported by a tape path component. The adjustmentcouplings couple the bracket to the base plate and are lockably settableto adjust and lock the spatial orientation of the magnetic head withrespect to a tape transported by the tape path components. Theadjustment couplings include upwardly extending posts on the bracket,with each post having a screwhole for receiving a screw. A springconcentrically surrounds each post and biases the bracket and the baseaway from each other. Screws extend through the base and into eachscrewhole. The turning of the screws adjusts the spatial orientation toadjust the zenith and the azimuth of the magnetic record head. Apenetration screw independently adjusts the penetration of the magnetichead with respect to the magnetic tape and the wrap angle. Onceadjusted, the screws maintain the spatial orientation, including theazimuth, zenith and penetration, of the magnetic head with respect tothe magnetic recording tape. Further details will become more apparentin the following description.

FIG. 1 is a line diagram depicting exemplary tape path components toschematically show the tape transport path and the tape drive apparatusof the present invention. Other components, such as motors, gears, etc.are not depicted so as not to obscure the components of the tapetransport path. The tape drive apparatus 10 includes a tape transportpath 12 that is indicated by the arrows. Components of the tapetransports path include the supply reel 14 of the tape cartridge and thetake up reel 16 of the tape drive. The magnetic recording tape 18 isguided between the supply reel 14 of the tape cartridge and the take upreel 16 of the tape drive 10 by the guide rollers 20 and fixed tapeguides 22. The tape 18 is transported past a magnetic head 24 isadjusted by a head positioner 26, which provides coarse and finepositioning. The alignment adjustments of the magnetic recording head 24are provided by the head alignment apparatus as will be described below.

The head positioner assembly 26 has a bracket 28 as depicted in FIG. 2,that is attached to a base 30 of the tape drive apparatus 10. Thebracket 28 is coupled to the base 30 by connectors (or “adjustmentcouplings”) 32, which will be further described. The guide rollers 20and fixed guides 22 may be seen in more detail in FIG. 2.

In linear magnetic tape recording, the data is written as tracks thatare parallel to the length of the tape or the tape path. The magnetichead 24 interfaces the tape 18 while the tape 18 is traversed at thenecessary speed. The magnetic head 24 interfaces with tape 18 and thewrite/read elements (not shown) of the magnetic head 24 perform thefunction of data recording. The perpendicularity of the head-gap withrespect to a data track is referred to as the “azimuth.” This may bestbe seen in the schematic depiction of FIG. 4A, which provides a linediagram of the tape tracks and the head-gap relationship. By definition,the centerline of the head-gap of the magnetic head 24 should beperpendicular to the tracks 25 on the tape 18. Any offset from this 90°relationship is termed an azimuth error. For example, if the angle was89°, a ˜1° azimuth error is present. If the angle were 90.5°, theazimuth error would be +0.5°. With the present invention, the magnetichead 24 may be moved in the directions of arrows 50 to adjust theazimuth error.

FIG. 4B schematically depicts a perspective side view of the magnetichead 24 and the tape 18 to illustrate a tilt of the magnetic head 24with respect to the plane formed by the beam of the tape 18. Any tiltfrom parallel to the plane is referred to as the zenith. Movement of themagnetic head 24 in the direction of arrows 52 adjusts the zenith.

Finally, in FIG. 4C, the penetration of the magnetic head 24 into thetape path of the tape 18 forms the wrap angle. The penetrationdirections are indicated by arrows 54.

The azimuth, zenith and penetration alignments must be within specifiedlimits in order to perform successful magnetic recording. FIG. 3 depictsthe head alignment apparatus in greater detail. The mechanism forpenetration adjustment is obscured in FIG. 3.

The adjustment couplings 32 include a pivot point coupling 34, anazimuth adjustment coupling 36 and a zenith adjustment coupling 38. Eachof the couplings 34, 36, 38 includes a cylindrical post 40 upwardlyextending from the bracket 28. Each of the posts 40 has a spring 42 thatconcentrically surrounds the post 40. Although not shown in FIG. 3, eachof the posts 40 has a central screwhole for receiving a screw.

The pivot point coupling 34 has a different construction, as shown inthe cross-section of FIG. 12, than the couplings 36 and 38, shown incross-section in FIG. 13. In the pivot point coupling 34, the post 40and the spherical washer 46 are in contact, so that there is no gap. Bycontrast, in the azimuth adjustment coupling 36 and the zenithadjustment coupling 38, the post 40 does not rest against the base 30nor against the spherical washer 46. Hence, there is always a gapbetween the base 30 and the post 40 at these two couplings 36, 38.

FIG. 5 shows an exploded view of the internal components of a tape driveassembly, and in particular, the adjustment couplings 32. With referenceto FIGS. 5 and 2 the adjustment couplings 32 include screws, 44, such asjackscrews or other types of screws, which screw into the screwholes inthe posts 40. The screws 44 extend through spherical washers, which seatwithin spherical seats 48. The spherical washers 46 provide resistancefrom any reasonable shook and vibration. The spherical washers, withspherical seats 48 and the preloading provided by the springs 42,prevents the alignment from moving after the alignment is set andsecured against shock and vibration. The use of jackscrews acting as thealignment adjusting mechanism and use of spherical washers provide anadded locking provision.

Referring back to FIG. 3, the pivot point coupling 34, once set, acts asa pivot for both the azimuth adjustment and the zenith adjustment. Theazimuth adjustment is an especially critical adjustment, and in theexemplary embodiment, a long lever arm is provided between the pivotpoint coupling 34 and the azimuth adjusting coupling 36. For example,the distance between the pivot point coupling 34 and the azimuthadjustment coupling 36 may be over 100 mm, and in especially preferredembodiments in 102 mm.

In practice, once the pivot point coupling 34 is set, rotation of thescrew 44 (e.g., a jackscrew) causes the bracket 28 to move about thepivot point coupling 34 in the direction of arrows 51 (i.e., essentiallywithin the plane of the drawing sheet). Once the azimuth is preciselyadjusted by rotation of the screw 44, the azimuth alignment is set andheld in place by the screw 44 and the spherical washer 46 in combinationwith the spherical seat 48. The pre-loading of the screw 44 by thespring 42 prevents changing of the azimuth against reasonable shock orvibration.

Similarly, to the adjustment of the azimuth, the zenith adjustmentcoupling 38 is effected by rotation of the screw 44 of the zenithadjustment coupling 38. This causes the bracket 28 to be moved slightlyin a plane orthogonal to that of the drawing around the pivot pointcoupling 34. The zenith of the magnetic head 24 will be thereby adjustedby a precise amount. After adjustment, the zenith alignment is held inplace by the spherical washer 46, the spherical seat 48 and thepre-loading spring 42.

The azimuth alignment screw 44 has metric threads of the size M3x.50.Thus, the screw will translate the post 40 of the azimuth adjustmentcoupling 36 of the main bracket 28 by 0.50 mm per one revolution of thescrew 44. The rotation occurs about the pivot point 34. With a 102 mm oflever arm between the azimuth adjustment coupling 36 and the pivot pointcoupling 34, there is a calculated resolution of 0.5 minutes of azimuthalignment for every 10° of rotation of azimuth screw 44. The zenithadjustment mechanics is similar, except that the lever arm between thescrew 44 of the zenith adjustment coupling 38 and pivot point coupling34 is 32 mm, in certain exemplary embodiments, although other lever armsizes are possible. Thus, the resolution of the zenith is 1.5 minutesfor every 10° of rotation of the zenith adjustment screw 44.

Each of the screws 44 is accessible from the topside of the driveapparatus 10. Hence, the alignment procedure may readily be one of thefinal assembly process steps for assembling the tape drive apparatus 10.Furthermore, in the event it becomes necessary to adjust the azimuth andzenith, removal of the top cover of the tape drive apparatus 10 androtation of accessible screws 44 readily accomplish this.

There is a space between the base plate 30 and the top if thecylindrical protrusion of the main bracket 28 at the azimuth adjustmentcoupling 36. This allows the azimuth point to move up or down dependingon the direction of rotation of the screw 44. The rotation of thebracket 28 occurs about the pivot point 34 as the azimuth pointtranslates in either an up or a down notion.

In addition to the alignment and zenith adjustments, the presentinvention provides for adjustment of the penetration of the head 24 intothe path of the tape 18. FIG. 6 provides a different perspective view ofthe tape drive apparatus 10 of the present invention, showing apenetration screw 56 that adjusts the penetration of the magnetic head24 into the path of the tape 18. The adjustment of the penetration isperformed independently of the adjustment of the azimuth and zenith.

FIG. 7 shows the head positioner 26 that includes the bracket 28 thatcarries a coarse positioner base 60. FIG. 8 depicts a fine positionerassembly 64 that carries a magnetic head 24. The fine positionerassembly 64 is carried on the coarse positioner base 60. The penetrationalignment screw 56, which includes a circular groove 58, screws into thecoarse positioner base 60.

As can be appreciated in FIGS. 8 and 10, the fine positioner assemblybase 64 includes dowel pins 66 that are guided by dowel pin guide slots62 located in the coarse positioner base 60. The fine positionerassembly 64 also includes a head-carriage suspension flexure 68 that isretained by a flexure retainer 70. The dowel pins 66 are located on thefine positioner assembly 64. The flexures and flexure retainer 70 arelocated on the fine positioner assembly 64 by the dowel pins 66. Afeature for the penetration alignment 72, shaped as a notch or recess,is provided on the flexure retainer 70. When the fine positionerassembly 64 is assembled onto the coarse positioner base 60, the dowelpin 66 is received in the dowel pin guide slots 62. The circular grove58 on the penetration screw 56 interacts with the feature 72 on theflexure retainer 70. Rotation of the penetration on screw 56controllably moves the fine positioner assembly 64.

Once assembled as a single assembly, the entire fine positioner assembly64, which includes the dowel pins 66, the flexure, and the flexureretainer 70, is translated to set the penetration of the head. Lineartranslation occurs via the interface between the slots 62 and the dowelpins 62. The slots 62 and the dowel pins 66 provide linear constraint.

Once properly positioned, screws 76 extending through a stabilizing bar74 interact with screwholes 80 on the fine positioner assembly 64 tofirmly lock down the position of the fine positioner assembly 64 on thecoarse positioner base 60.

FIG. 9 shows an embodiment of the flexure retainer 70 in isolation. FIG.10 shows an exploded view of the head positioner assembly 26 inaccordance with embodiments of the present invention. FIG. 11 depictsthe head positioner assembly 26 after it has been assembled.

The present invention provides for the adjustment and locking of thespatial orientation of a magnetic head with respect to a tapetransported by tape path components of a tape drive apparatus. This isachieved in a manner that is readily accessible, precise, and providesreasonable securement against unintended changes in the alignment.

Although the present invention has been described and illustrated indetail, it is to be clearly understood that the same is by way ofillustration and example only and is not to be taken by way oflimitation, the scope of the present invention being limited only by theterms of the appended claims.

1. A tape drive apparatus with head alignment system, comprising: a baseplate; tape path components on the base plate: a bracket adjustablycoupled to the base plate, wherein the bracket carries a coarsepositioner base that carries a fine positioner assembly that carries amagnetic head for reading and writing to a tape transported by the tapepath components; and an alignment screw that screws into the coarsepositioner base, wherein the screw, coarse positioner base, and finepositioner assembly are configured for adjusting the penetrationorientation of the magnetic head with respect to a magnetic tape.
 2. Theapparatus of claim 1, further comprising means for adjusting the azimuthand zenith spatial orientation of the magnetic head with respect to themagnetic tape.
 3. The apparatus of claim 2, further comprising: a baseplate; tape transport apparatus on the base plate; a bracket thatcarries the magnetic head; and connectors that connect the bracket tothe base plate by an adjustable distance. 4-10. (canceled)
 11. A tapedrive apparatus comprising: a base plate; tape path components on thebase plate; a bracket adjustably coupled to the base plate, the bracketcarrying a magnetic head for reading and writing to a tape transportedby the tape path components; and adjustment couplings that couple thebracket to the base plate and are lockingly settable to adjust and lockthe azimuth and zenith spatial orientation of the magnetic head withrespect to a tape transported by the tape path components, wherein thecouplings are accessible for adjustment from the top side of the tapedrive apparatus. 12-20. (canceled)
 21. A tape drive apparatus comprisinga base plate; tape path components on the base plate; a bracket coupledto the base plate, the bracket carrying a coarse positioner base whereinand the coarse positioner base further comprises a flexure retainer anddowel pin guide slots; a fine positioner assembly carried by the coarsepositioner base, wherein the fine positioner assembly further comprisesdowel pins; a magnetic head carried by the fine positioner assembly,wherein the magnetic head enables reading and writing to a tapetransported by the tape path components; an alignment screw that screwsinto the coarse positioner base, wherein the screw is configured forinteracting with a notch-shaped feature of the flexure retainer and formoving the fine positioner assembly with its dowel pins received in thedowel pin guides; and means for adjusting the azimuth and zenith spatialorientation of the magnetic head with respect to the magnetic tape. 22.A tape drive apparatus comprising a base plate; tape path components onthe base plate; a bracket coupled to the base plate, the bracketcarrying a coarse positioner base that carries a fine positionerassembly that carries a magnetic head for reading and writing to a tapetransported by the tape path components; an alignment screw that screwsinto the coarse positioner base, wherein the screw, base, and assemblyare configured for adjusting the penetration orientation of the magnetichead with respect to a magnetic tape; and means for adjusting theazimuth and zenith spatial orientation of the magnetic head with respectto the magnetic tape.
 23. The apparatus of claim 22, wherein the meansfor adjusting the azimuth and zenith spatial orientation of the headfurther comprises a pivot point coupling,;an azimuth coupling, and azenith coupling between the base plate and the bracket and wherein eachof the pivot point, azimuth, and zenith couplings are lockinglysettable.
 24. The apparatus of claim 23, wherein the tape driveapparatus has a top side and each of the pivot point, azimuth, andzenith couplings are accessible for adjustment from the top side. 25.The apparatus of claim 23, wherein the pivot point, azimuth, and zenithcouplings each comprise an upwardly extending post on the bracket, thepost having a screwhole for receiving a screw; a spring, concentricallysurrounding the post, bearing at opposite ends of the spring against thebracket and the base plate to bias the bracket and the base plate wayfrom each other; and a screw extending through the base and into eachscrewhole.
 26. The apparatus of claim 25, wherein the pivot point,azimuth, and zenith couplings each include a spherical seat on the baseplate and a spherical washer on the screw, such that the sphericalwasher interacts with the spherical seat.
 27. The apparatus of claim 25,wherein the tape drive apparatus has a top side and each of the screwsare accessible for turning from the top side.
 28. A tape drive apparatuswith head alignment system, comprising: a magnetic head; means foradjusting the means the azimuth and zenith spatial orientation of themagnetic head with respect to a magnetic tape; and means for means foradjusting the penetration spatial orientation of the magnetic head withrespect to the magnetic tape.
 29. A method for aligning a magnetic headin a tape drive apparatus comprising: adjusting the azimuth, and zenithspatial orientation of the head with respect to a magnetic tape, byscrewing or unscrewing a screw into a pivot point, azimuth, or zenithcoupling, wherein each of the couplings couples a base plate in the tapedrive apparatus to a bracket; and adjusting the penetration orientationof the head with respect to the magnetic tape, by screwing or unscrewinga screw into a coarse positioner base that carries a fine positionerassembly that carries the magnetic head, wherein the coarse positionerbase is carried by the bracket.